How should we relate user story points in hours in Agile?

Story points and hours cannot be related to each other.

By translating Story Points to hours you stop benefiting from the speed of relative estimation. 

I have been working as an agile scrum development team member last five years in two different companies they are very mature in agile software development.

 

In both companies how they have been relating the story point with hours as below :

 

The fact behind this is almost every company works for 8 hours per day. Many companies believe that only 6.0 to 6.5 hours is productive hours out of 8 hours because we have to exclude lunchtime, email, meeting, and others unproductive hours from total working hours.

What are the benefits to relate story point in hours are as below :

This is also purely based on the previous history of time log against the completed user stories. How much hours spent to complete a story points will give you rough idea on hours for each story points.